Question about copyright for vintage images

Hi people, I’d like to start making auction templates for ebay to sell. But a few things in mind, and need your heip.
Does anyone know of any sites that you can find graphics, backgrounds, fonts, etc. for commercial use? I am confused a little about using vintage graphics. I’ve seen many people selling vintage graphics. If they were made before the copyright laws and are considered public domain, how are people able to sell these and put their own copyright on them? Aren't they public images? I know people get them from greeting cards etc. What if you had the same greeting card (because I am sure more than one was printed), can you use the image? For example, a painting of a rose. I feel like this is such a general image.
Also, what about basic stuff like dots or stripes, there is nothing original about them.
Hopefully someone could clear this up for me or direct me to a good site or book to find the info. I have been searching for months and everything seems so ambiguous

All images u can find on google and so on are copyrighted. All of them have a owner. You can't resell something that is not made by u.
If you want to be original and pro ry to design everything, from a scratch. Then you won't have problem with the copyright. The dots, lines and colors are not copyrighted. LoL. So if you want to sell designs try to make them, then sell. Don't take images from sites and sell them somewhere else.

This is a difficult question. I think the copyright for images is something like the life of the artist plus 70 years but I guess many works aren't attributed to a known artist. You really need to see a lawyer who specializes in copyright law to answer you question otherwise you may find yourself being sued. There are a lot of great sites that will sell vintage images as framed posters. What they do about the copyright aspect is a very good question though ...It would be a good idea to find out more.